This invention relates to air conditioning systems for conditioning the air in a plurality of areas or spaces in a common enclosure, and more particularly, relates to a ceiling air terminal which is provided for delivering the conditioned air into an individual space.
In recent years many multi-zone buildings, such as schools, offices, apartments, and hospitals have employed central station air conditioning systems to provide conditioned air to regulate the psychometric properties of the air in each of the zones of the building. One air conditioning system that has enjoyed wide-spread commercial success is known as a dual conduit system. A dual conduit system is designed to supply two air streams to enclosed areas or rooms that have a reversing transmission load; that is, during summer, heat flows from the ambient air into the building, whereas during winter, heat flows from the building to the ambient air. One air stream, called the secondary air is cooled the year round and is constant in temperature and variable in volume. The other air stream, called the primary air, is constant in volume and the air temperature is varied; it is warm in winter and cool in summer. Primary air is, therefore, a constant volume-variable temperature air stream. To obtain the two air streams, central station apparatus are employed to provide the air temperature and volumes required.
The primary air apparatus varies the psychometric properties of the air supplied thereto, which may comprise a mixture of outdoor and return air. The apparatus includes filters to remove dirt or foreign matter entrained in the air, preheat coils as required to temper cold winter air, a humidifier to add winter humidification and a dehumidifier to remove excess moisture and to cool the supply air furnished at a constant volume to the enclosed areas contained in the building.
The secondary air apparatus also varies the psychometric properties of the air supplied thereto and supplies either all return air, a mixture of outdoor and return air, or all outdoor air, depending upon the season. The apparatus contains filters to remove dirt or foreign matter entrained in the air and a dehumidifier to remove excess moisture and/or to cool the supply air.
A refrigeration machine is necessary to complete the overall system. Any of the three basic refrigeration cycles, absorption, reciprocating, or centrifugal may be considered for the refrigeration equipment. Either chilled water from the refrigeration machine or direct expansion of refrigerant may be used to obtain a desired temperature for the supply air. The foregoing system is completely described in U.S. Pat. No. 2,609,743, issued Sept. 9, 1952, in the names of Carlyle M. Ashley and William T. McGrath.
Heretofore, it has been the practice to provide at least two separate air discharge terminals in each of the individual enclosed spaces. One of the terminals is connected to the source of primary air and serves the peripheral portion of the space or room. The other terminal is connected to the source of secondary air and serves the interior portion of the space. The initial cost for the air conditioning system heretofore described has thus been relatively expensive. In addition, the terminal servicing the peripheral portion of the room has heretofore been typically installed under the window or adjacent to the peripheral wall, thus generally occupying a portion of the otherwise usable floor space of the room. Furthermore, since the peripheral terminals have been so installed, architects have been somewhat inhibited in designing buildings having dual conduit systems.